Post by Uncle Buddy on Mar 31, 2013 17:21:23 GMT -8
Thanks George, those are very good documents to study. I especially liked this quote from the pdf (which is in ENGLISH by the way, so everybody please download and read it):
"The direct entrainment of a low velocity suction fluid by a motive fluid results in an unavoidable loss of kinetic energy owing to impact and turbulence originally possessed by the motive fluid. This fraction that is successfully transmitted to the mixture through the exchange of momentum is called the entrainment efficiency."
This supports the statement I made recently (which I gleaned from an abstract of a technical article many years ago) that a jet pump works much differently if air is mechanically pumped into the suction port. Otherwise, as stated here, the low velocity suction fluid dilutes much of the drive fluid's kinetic energy. I would expect the entrainment efficiency of a pumped-suction jet pump to be several times higher than the typical case, where the drive fluid must overcome the inertia of the suction fluid.
The patent you linked looks EXTREMELY INTERESTING and simple to understand. I will read it as soon as I have time, hopefully today. It definitely looks like MIND CANDY for us revolutionary inventor types.
Post by Uncle Buddy on Mar 31, 2013 20:24:23 GMT -8
That multi-stage ejector design is simple, and awesome. He is doing what has not been done before. This ejector would for our purposes be changed to a thermal compressor to force air into a tank instead of evacuating a tank or other space.
This is a very cool jet pump.
I like the way that the final stage, which in the drawing is shown to be driven by the same air as the first stage, could actually be driven by ambient air! Because by then the pressure is so low that the differential is large between drive nozzle and suction port, even using ambient air as drive fluid.
This THERMOCOMPRESSOR patent, which was bought by Ingersoll-Rand, confirms my recent statement that there will be massive change of temperature of the drive fluid in a jet pump, depending on the nozzle geometry. My statement was in regards to condensation of high pressure drive air into liquid form, as a direct analogy of the boiler injector which condenses the drive steam.
THIS IS A GOOD BOOK, it contains over 400 abstracts of technical articles about jet pumps. I don't have it anymore. Several years ago after my appendix exploded I gave all my paper to the recycling man and gave my filing cabinets to the local thrift shop. Since then I am all electronic and rarely use my laser printer, and never buy books. Anyhow, this is a good book if you can find a copy in an engineering library at your local university:
S.T. Bonnington and A.L. King, Jet Pumps and Ejectors, a State of the Art; Review and bibliography (2nd edn). BHRA Fluid Eng, Cranfield, Bedford UK, 1976.
EMINENT SCIENTIST JEAN BERTIN patented this device which is supposed to put low pressure fluid into a higher pressure zone (sound familiar?). US Patent 2565907. I don't remember where I heard of him before, maybe in the pulsejet field.
It's almost 1 am and I just got an instant reply from an inventor I sent a query to. Didn't expect that, there's no rest for the weary.
There might be some connection. The pulsejet (V1) was first patented when Neal was a small child, so he cannot be blamed for the pulsejet, but the Germans might have learned something from him whether he liked it or not.
The scientist Jean Bertin who I mentioned above was the inventor of the French Escopette, a valveless pulsejet. One way fluid motion without check valves, sounds impossible doesn't it? The French and the Germans invented the pulsejet simultaneously, but the Escopette had no check valves. This is reminiscent of Tesla's valvular conduit, and the technology is now called "fluid diode" and there are a variety of ways to increase the flow resistance in one direction, without using check valves.
A lot of fluidic devices are interesting and sometimes I wonder if they are published and patented as "fluidics" or fluid logic circuits to keep people from getting interested in what they are actually doing. For example, Robert B Hammett, who wrote a design manual on double check valve type acoustic compressors, was not the only one. Another was an award-winning government scientist who patented pretty much the same thing but called it a fluidics device, fluid amplifier or something.
See my book Piston Made of Air for more on pulsejets, Kadenacy effect, etc.
Will high pressure jet pump drive air LIQUEFY (condense) in the jet nozzle?
I have to go over the math for Bernoulli Effect, though in the past it hasn't really done me any good, since I seem to be allergic to math as presented on wikipedia.
I have, however, looked at it from the viewpoint of a statics formula, Charles Law, and it looks like a flow of 1500 psi air, if it can be speeded up enough in a nozzle to reduce it to atmospheric pressure, would reach -320 deg F and liquefy. With a density hundreds of times more than gaseous air, and full of latent heat energy, I think a high pressure jet pump or thermocompressor is all that's needed to put low pressure air into a high pressure tank.
Not conclusive yet, my math needs to be upgraded for sure, but it was fun to start at least. Not as much fun as shoveling pig shit, which I was doing earlier in the evening, but there's only so much fun a person my age is able to have after dark.
I have an engineering analysis on why the Giffard injector can do what it does if anyone wants it. It's in French and I've done a preliminary translation on it, also there is some calculus I think. The main reasons the boiler injector works are 1) energy can't be destroyed, so the energy coming out of the injector is the same as the energy going into it, and 2) condensation of steam in the injector creates much denser and highly energized water which is the real drive fluid. The energy is delivered to the injector by steam from the same boiler, but the work of putting the fresh water into the boiler is really done by condensed steam--hot water--not by steam.
The Giffard injector works so well that it doesn't even need maximum steam pressure to function.
Post by Uncle Buddy on Apr 12, 2013 17:13:28 GMT -8
Newt said: "Re: liquid air and latent heat of vapourisation, as you said these other ideas could also be all or part of how this thing works, but note water has a latent heat of 2000 J/kg and air only 200 (I think). This may make the Gifford analogy more difficult to work with air. I was trying to explain Neal's device to a friend who was quite sceptical but the also said "Oh - you mean like a ram pump for air?" - I know the Unc also draws parallels with the hydraulic ram , low pressure to high pressure water pump thingy."
I've posed a question on an engineering answers forum where I occasionally go for more than my fair share of abuse, and have not been surprised that no one has addressed the actual question, the core of the argument, as to whether it is possible for air in a nozzle to get cold enough to momentarily condense, and if so, then how do we compute that low temperature? It was like pulling teeth to try and get a few of the respondents to at least say, "I don't know," or something approaching that. It is more to the engineers' temperament to compare my ignorance to theirs and tell me to go back to school, which of course I can't do since I've moved to the Philippines and started a family, on the basis of a social security check that el presidente obama would like to take away so he can afford to send a drone to my house, kerboom.
Now Newt has given me the first hint of new usable information. It sounds to me like the vast latent heat of H2O is not so vast with air. This is to be expected, since air doesn't hold as much heat as water; the specific heat is also much lower. The specific heat of air is 0.2375 BTU to change the temperature of one pound of air one degree F. For water it's 1.0. That's from memory, please correct me if I'm wrong. Now Newt informs me that the latent heat is also ten times less for air than water.
For anyone who doesn't know, I will put my ignorance on display by trying to explain what specific heat and latent heat are. If you try to change the phase of a substance from liquid to gas, from solid to liquid, either direction, you have to heat or cool the substance a certain amount of heat energy for each degree of temperature change. Understanding this depends on realizing that heat energy and temperature are not the same thing. This amount of heat energy required is called the specific heat, and each substance has its own. Also, since I am an old, uneducated Amerikano I use old fashioned units, not the SI units that engineers use. In my units of BTU and Fahrenheit degrees, it takes 1 BTU per degree F of thermal energy to heat or cool water. For air (at constant pressure, with the volume allowed to expand) the specific heat is 0.2375 BTU per degree of temp change.
But the rules change when the actual boiling point, freezing point, or condensation point of temperature is reached. At this point, many many extra units of thermal energy must be pumped into or out of the substance to change its temperature that one more degree so that it will actually freeze, thaw, condense, boil, liquefy, etc. This additional energy, or latent heat, is then stored in the vaporized substance or liberated from the condensed substance and still present in the hot water or whatever the substance has become. For example in the boiler injector, when the steam condenses, the heat energy that had once been used to vaporize it from the liquid state is liberated from the steam and now resides in the water. So the resulting water is literally energized by the latent heat, and this accelerates it all the more in the nozzle, giving it the energy it needs to put itself back into the boiler.
I'll look up the latent heat and see if Newt's numbers are correct. If so, then doesn't it mean that ten times more air mass would have to be condensed in an air tank injector than the amount of steam that would have to be condensed in a boiler injector? Maybe not. Because what if air is ten times easier to pump than water? These generalities should be dealt with as generalities, logic problems, before getting embroiled in math, because ten times more people will be willing to read and comment if they don't see any math in the post!
I should also mention that one main purpose of the Giffard analogy is only and simply to tell us whether there is anything to be gained by bothering to study the Giffard injector, how it functions, what the math looks like, etc. I am not saying that air-to-air thermocompressors have to condense air in order to work; we know that is not the case. The illustration and short description from the Hiscox text should be enough to have everyone scrambling to see (in their garage and machine shop) how far this principle can be extended. And how to put a compressor inside a tank.
Thanks Newt for having more to contribute than a whole room full of engineers. I will see if they have anything to say about the comparison of latent heat between steam and air. I still need to find a reference that explains how cold air will get in a jet due to changing pressure as the nozzle area changes. I DON'T believe that the air can't reach 320 deg below zero F in a nozzle. Happy to replace my opinion with facts.
Here is a good product catalog from a company that actually makes boiler injectors. For those who won't click the link, here are some quotes:
"...utilizing the velocity and condensation of a jet of steam from the boiler to lift and force into the same boiler a jet of water many times the weight of the original jet of steam..."
"...It is not dependent upon an outside source of power..."
"...Unit is compact, has no mechanically operated parts and requires no foundation or floor space..."
"First cost and maintenance are low."
"Operating steam is condensed and returned to the boiler resulting in a thermal efficiency of nearly 100%."
"Dependable in operation."
Remember, the giffard injector was the laugh of Techtalktown long after it was readily available at Boilers-R-Us. It is CLEARLY impossible to put cold water into a hot boiler without a mechanical pump, no???
Sorry if I've been muddling topics on threads. Glad you took my comments as they were meant, just my resistance to the ideas, and therefore to be discussed, not a dismissive "it'll never work". I really like that so many for so long could not believe in the Giffard device and it gives hope that there are quirky things still to be found out and understood.
I like that you use BTU (British Thermal Units) as an American abroad and I don't as a Britain in Britain. Only because my schooling was in SI units. I still use miles and often feet and inches for little carpentry DIY stuff and sometime lb and oz for cooking. And pints in a pub.
I must read more, but I just tried a quick Giffard refresher on wikipedia and have decided I really still don't quite get it. It is like magic! There was something about the mass of steam vs air that increases kinetic energy that I thought would be a problem with high pressure air entraining low pressure air but there was this - "The air ejector or venturi pump is similar to the steam ejector but uses high-pressure air as the working fluid. Multistage air ejectors can be used, but since air cannot easily be condensed at room temperature, an air ejector is usually limited to two or three stages."
So high pressure air (instead of steam) can indeed create vacuums but can it pressurise like Neal's device? Also they say the same principle is used to move bulk grain and powder which wont have any latent heat, so maybe latent heat 10 fold less than water is no problem?
I also wondered if as steam in air entraining water works so well, would air in helium entraining liquid air work??
Sorry you not been well and hope yr back on 14 cylinders soon!
Maybe I should keep my comments to myself until I've read more. I really want to join in and stimulate discussion but am not prioritising reading time first. I've just looked back in this thread to see things I should've read. I'll try and get on with it soon.
Post by Uncle Buddy on Apr 13, 2013 17:34:54 GMT -8
Newt, don't worry about posting the right thing in the right place, etc. Keeping the discussion alive is by far more important than the rules, and there are no rules, so there you go. Happy to have you.
Any fluid can be used to entrain fluids and solids in a venturi pump, assuming that reality is dealt with. That's where the math comes in. Air is commonly disparaged, and this attitude is taught to engineers in school I believe, by comparing it with steam. Because of its relatively low specific heat, it gives up heat quickly and becomes "too cold" to do anything. This is where the engineering establishment has lost touch with reality do to industrial hearsay in lieu of doing the math, in lieu of a willingness to think original thoughts.
There is some possibility that Neal had an injector and didn't mention it in the patent. This is quite true of Soro, his patent never mentions an injector, but when his financiers stole his injector, he sure raised a stink about it! Des Hill and others also mention injectors but not in any detail. The main reason to consider Neal as a user of injectors is because of the most mysterious statement in his patent, the last paragraph before the final claims, which goes something like this: "Outside air pressure source can be coupled with the tank to augment that pressure derived from the cylinders of the engine." I believe this statement should take center stage at some point in our deliberations. The patent attorney reminded the patent examiner that the statement had been made, after three refusals to grant the patent. If nothing else, it could have just been tagged on to prevent the patent office from shrugging it off as a perpetual motion scheme, but we can't assume this. It deserves some consideration, and the sentence should be examined in detail, each word weighed carefully.
However, my main reason for suddenly getting interested in the Giffard injector (again) is that Bill Truitt's three tanks were never allowed to go under 1000 psi. The use of an injector is thus suggested, though I have had other brainstorms about that recently.
Have finished reading a good text on injectors, Practice and Theory of the Injector, Strickland L. Kneass, 1894. A hardcopy was given to me as a gift, but it is also available online free from Google Books/Google Play. Yes, the injector for steam water supply was a great innovation for steam boilers. The source of energy to drive the injector is steam, which contains much energy, especially when it condenses to release that energy. I must admit that I do not see how air alone would work the same way since the incoming air does not contain this amount of energy. If the air was made to condense then it would be a different story, but that requires high pressures and very low temperatures. If somebody out there understands this differently, please tell me about it, that would be much appreciated. Here are a couple of excerpts from that text, regarding the difference between a liquid/steam and a gas like air: Practice_and_theory_of_the_injector4.pdf (124.78 KB)
Post by Uncle Buddy on Sept 29, 2014 19:12:10 GMT -8
I'm not suggesting that air and steam devices would be similar or that they would load their respective vessels in the same way. I am suggesting that what has so long been done with steam (the general result, not the hardware) can be done with air.
I've tried to get information on whether an air injector with a very high drive pressure would cause any liquefaction upon the air's accelerating in the nozzle, losing pressure and getting very cold. I don't think I ever got an answer, though I tried several places online. This was going to be my new Truitt theory, since he keeps his tanks above 1000 psi. Anyway, if there was any liquefying going on in a single-stage (?or multi-stage) nozzle, then Giffard might be a more direct analogy to what we want to do.
Not to take away from Neal, which I have always felt needs to be reproduced fairly close to the patent first, before being improved on.
I still think an injector might be needed only to start Neal to functioning, then shut off once resonance is attained.
The point I was attempting to make was that the injector requires some high pressure source that already required some high amount of energy to create in the first place. With Potter, we see how the extremely lossy change from high 1000 psi to a working pressure like 150 psi could be made to be less lossy, using the injector. But overall, we are still talking about lossy effects. This is different than the whole overunity effect, which needs to extract ambient energy from the atmosphere. The injector is a useful tool, and it may have a place in some air machine, but I do not see how the injector can bring about the overunity effect, that was my only point. It does have it's place, as a means to reduce some lossy part of the machine. Lossy, meaning energy is being lost. That is my current understanding, but always subject to correction if someone out there can explain differently!